Garden Calendar: Dig and store summer-flowering bulbs for winter

Elephant ears and canna lilies add a great tropical look to the garden with their broad and sometimes bright leaves, but Kansas winters are generally a little too much for them. Instead of leaving them outside to freeze, though, you can easily overwinter their bulbs in a dry basement, garage or a cool spot in your house.

Caladiums, gladiolus, dahlias, tuberous begonias and calla lily bulbs should be handled the same way as elephant ears and cannas. All of these plants are generally referred to as summer-flowering bulbs. Another common classification of bulbs is spring-flowering varieties like tulips and daffodils. For a nice multiseason display, you might remember to plant your spring-flowering bulbs about the time you are digging the summer-flowering ones.

To overwinter summer-flowering bulbs, cut back the browned, post-frozen foliage and dig the roots. You can also cut back the long fibrous roots, as you are mainly looking to save the main storage organ. (Although I and other horticulturists often use “bulb” as a general term for these specialized roots, some of them have other official names.)

Place the bulbs in a garage, shed or shady, protected location and let them dry out for about a week. Gently remove large chunks of soil that are stuck to the roots to prevent decay, although it is unnecessary to completely clean them.

Once the bulbs are clean, wrap them in newspaper or pack them in peat moss, vermiculite or perlite (available at local garden centers near the potting media).

Elephant ears, cannas, gladiolus, dahlias, tuberous begonias and calla lilies can all be stored at about 40 degrees Fahrenheit. Caladiums need a little warmer environment and should be stored in a location that remains 50 degrees to 60 degrees through the winter.

As previously mentioned, “bulb” is a general term often used by horticulturists to refer to a specialized organ or type of root that stores nutrients and water for the plant. There are different types of storage organs. On cannas and calla lilies, the organ is called a rhizome. On gladiolus, the organ is a corm. Elephant ears, caladiums and tuberous begonias produce tubers. Dahlias are referred to as a tuberous-rooted plant.

Occasionally, elephant ears and other plants that grow from bulb-like structures do not actually produce a bulb or other storage organ. This may be because the plant did not have any excess resources throughout the growing season that could be stored.

If you attempt to dig your summer-flowering bulbs and just find what look like regular roots and stems, you may not be able to store these. You can dig the roots and attempt to dry and wrap them in a clump as described above, and it may still produce a plant next spring. In this case, check the root clumps occasionally and lightly mist them if they become very dry. Too much moisture can lead to decay, but they will also lose their viability if they completely dry out.

Elephant ear is also a general name given to a group of plants with giant leaves — presumably the size of an elephant’s ear. Plants in the genus Colocasia are most often given this name, although Alocasia plants are also called elephant ear. Taro is another name used interchangeably for these plants. There are differences between Colocasia and Alocasia, but even I confuse the two at times. Purists may reference minor distinctions in leaf tips, petioles and environmental preferences. Both will add a unique focal point to your garden.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. She can be reached at 843-7058 or